Most virus protection systems slow down the computer as they continuously check all reads and writes through network and inside the computer. In most cases that's not needed as we don't want to start/use the downloaded content (e.g. we just watch a clip on youtube etc.).

In case of Sandboxie everything goes lightweight: I can be sure that anything I do, try, check inside sandboxie will not affect my computer, it is 100% protected from viruses and any threats. If I am sure that I want to download something for later use (e.g. a PDF file) then it is just one click to save out that from my sandbox. If there is to much garbage I made, then I just click "empty my sandbox" and its clean, ready to start again. Great application!

I also installed Sandboxie on my wife's computer, and she understood the way of Sandboxie works in minutes. She is today one of the greatest fans of this application, she uses it every day.